R help - Feb 2013 - why "object 'x' not found"?

Dear Listers,

I try to change the structure of my data. i have an indicator-matrix and
want to end up with a factor.

i have

v1 v2 v3
1   0   0
0   1   0
0   0   1

and want

v1 v2 v3  v4
1   0   0   1
0   1   0   2
0   0   1   3

amongst other things i tried the following

d <- data.frame(d1=c(1,0,0), d2=c(0,1,0), d3=c(0,0,1))
d$nr <- NA
sapply(1:3, function(x) ifelse(get(paste0("d$d",x))==1,x,d$nr))
>From R i get the message "Object 'd$d1' not found".
But why, it's there?

Thanks a lot.
Winfried

	[[alternative HTML version deleted]]

try this:
> x <- read.table(text = "v1 v2 v3
+ 1   0   0
+ 0   1   0
+ 0   0   1", header = TRUE)
>
> x$v4 <- apply(x, 1, function(a) which(a == 1))
> x
  v1 v2 v3 v4
1  1  0  0  1
2  0  1  0  2
3  0  0  1  3
>
>
>

On Thu, Feb 7, 2013 at 1:20 PM, Winfried Moser <winfried.moser at
gmail.com> wrote:
> Dear Listers,
>
> I try to change the structure of my data. i have an indicator-matrix and
> want to end up with a factor.
>
> i have
>
> v1 v2 v3
> 1   0   0
> 0   1   0
> 0   0   1
>
> and want
>
> v1 v2 v3  v4
> 1   0   0   1
> 0   1   0   2
> 0   0   1   3
>
> amongst other things i tried the following
>
> d <- data.frame(d1=c(1,0,0), d2=c(0,1,0), d3=c(0,0,1))
> d$nr <- NA
> sapply(1:3, function(x) ifelse(get(paste0("d$d",x))==1,x,d$nr))
>
> >From R i get the message "Object 'd$d1' not found".
> But why, it's there?
>
> Thanks a lot.
> Winfried
>
>         [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.


-- 
Jim Holtman
Data Munger Guru

What is the problem that you are trying to solve?
Tell me what you want to do, not how you want to do it.

On 07/02/2013 1:20 PM, Winfried Moser wrote:
> Dear Listers,
>
> I try to change the structure of my data. i have an indicator-matrix and
> want to end up with a factor.
>
> i have
>
> v1 v2 v3
> 1   0   0
> 0   1   0
> 0   0   1
>
> and want
>
> v1 v2 v3  v4
> 1   0   0   1
> 0   1   0   2
> 0   0   1   3
>
> amongst other things i tried the following
>
> d <- data.frame(d1=c(1,0,0), d2=c(0,1,0), d3=c(0,0,1))
> d$nr <- NA
> sapply(1:3, function(x) ifelse(get(paste0("d$d",x))==1,x,d$nr))
>
> >From R i get the message "Object 'd$d1' not found".
> But why, it's there?
No it's not there.  There's a variable called d, but no variable called 
d$d1.  That's an expression to extract the d1 component from d.
You could parse and eval that expression, but surely it's not the right 
way to do this.  In your simple example,  using d[[x]] would work.  In a 
more complicated one, you might want something like

components <- names(d)
d[[components[x]]]

Duncan Murdoch

Hi,
You could get the result:
dat1 <- read.table(text = "
v1 v2 v3
?1?? 0?? 0
?0?? 1?? 0
?0?? 0?? 1
",sep="",header=TRUE)

dat1$v4<-apply(mapply(`==`,dat1,1),2,which)
?dat1
?# v1 v2 v3 v4
#1? 1? 0? 0? 1
#2? 0? 1? 0? 2
#3? 0? 0? 1? 3
A.K.




----- Original Message -----
From: Winfried Moser <winfried.moser at gmail.com>
To: r-help <r-help at r-project.org>
Cc: 
Sent: Thursday, February 7, 2013 12:20 PM
Subject: [R] why "object 'x' not found"?

Dear Listers,

I try to change the structure of my data. i have an indicator-matrix and
want to end up with a factor.

i have

v1 v2 v3
1?  0?  0
0?  1?  0
0?  0?  1

and want

v1 v2 v3? v4
1?  0?  0?  1
0?  1?  0?  2
0?  0?  1?  3

amongst other things i tried the following

d <- data.frame(d1=c(1,0,0), d2=c(0,1,0), d3=c(0,0,1))
d$nr <- NA
sapply(1:3, function(x) ifelse(get(paste0("d$d",x))==1,x,d$nr))
>From R i get the message "Object 'd$d1' not found".
But why, it's there?

Thanks a lot.
Winfried

??? [[alternative HTML version deleted]]

______________________________________________
R-help at r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.

On Feb 7, 2013, at 10:20 AM, Winfried Moser wrote:
> Dear Listers,
> 
> I try to change the structure of my data. i have an indicator-matrix and
> want to end up with a factor.
> 
> i have
> 
> v1 v2 v3
> 1   0   0
> 0   1   0
> 0   0   1
> 
> and want
> 
> v1 v2 v3  v4
> 1   0   0   1
> 0   1   0   2
> 0   0   1   3
> 
> amongst other things i tried the following
> 
> d <- data.frame(d1=c(1,0,0), d2=c(0,1,0), d3=c(0,0,1))
> d$nr <- NA
> sapply(1:3, function(x) ifelse(get(paste0("d$d",x))==1,x,d$nr))
> 
>> From R i get the message "Object 'd$d1' not found".
> But why, it's there?
No, it's not "there". There is nothing with that name. At the
console `d$d1` is a function being applied to 'd', whereas the `get`
function expects a character argument or something that evaluate to a character.
This is somewhat similar to what you were attempting and syntactically succeeds:
> sapply(1:3, function(x) ifelse(d[[ paste0("d",x) ]]==1,x,d$nr))
     [,1] [,2] [,3]
[1,]    1   NA   NA
[2,]   NA    2   NA
[3,]   NA   NA    3

Notice that the '[[' function is superior in every way to the
'$' function.

-- 
David.